Dresden 2003 – wissenschaftliches Programm
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CPP: Chemische Physik und Polymerphysik
CPP 22: POSTER C
CPP 22.6: Poster
Donnerstag, 27. März 2003, 12:00–14:00, ZEU/250
Single molecule spectroscopy on the antenna complex of the purple bacterium R. rubrum — •Britta Götze1, Uwe Gerken1, Carsten Tietz1, Jörg Wrachtrup1, Domenico Lupo2, and Robin Ghosh2 — 13. Physikalisches Institut, Universität Stuttgart — 2Biologisches Institut, Abt. Bioenergetik, Universität Stuttgart
The light harvesting 1 (LH1) complex from the purple bacteria Rhodospirillum rubrum comprises 32 strongly coupled bacteriochlorphyll molecules arranged in a rinlike aggregate of C16 symmtery. In the case of undisturbed symmtery one expects excitonic states where the exciton is delocaliced over the whole aggregate. The polarization properties of a single complex are extremely sensitive way of measuring the distortion of symmetry. The complexes were either solubilized in a detergent micelle or reconstituted in di-oleoyl-sn-phosphatidyl-choline (DOPC) single lamellar vesicles resembling their natural environment. Vesicles and micelles were immobilized on mica.
Fluorescence excitation spectra of single LH1 complexes in membranes at low temperature reveal that most of the complexes show very slight distortions of symmetry. In contrast, single complexes in a detergent micelle and immobilized on a mica surface show a much more unstable spectral behavior. As a next logical step whole core-complexes, consisting of a light harvesting complex 1 and a rection center, are studied.The above-mentioned measurements are also performed on these core complexes to gain information about changes in the spectral behavior of the light har-vesting complexes in presence of the reaction center.